Submitted to: Phycologia Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2003
Publication Date: 9/1/2003
Citation: Leblond, J.D., Evens, T.J., Chapman, P.J. 2003. The biochemistry of dinoflagellate lipids, with particular reference to the fatty acid and sterol composition of a karenia brevis bloom. Phycologia. 42(4):324-331. Interpretive Summary: Karenia brevis, the Florida red-tide alga, frequently forms large, toxic blooms, which are responsible for massive fish kills and multiple public health concerns. Despite decades of field studies, very little information is known about the physiology of this organism; no investigation has yet examined the lipid composition of a naturally occurring bloom of this alga. This study concerns the analysis of samples for fatty acid and sterol composition from a K. brevis bloom that occurred in 1999 off the coast of northwest Florida. Fatty acids found in lipid fractions containing membrane (phospho)lipids, chloroplast-associated (glyco)lipids, and storage triglycerides, respectively, differed significantly. Although the fatty acid and sterol compositions of these samples are very similar to those observed in laboratory cultures of this organism, the information obtained in this study raises a number of salient questions about the roles of lipids in the physiology of K. brevis. The results of this study are important to harmful algal bloom (HAB) researchers, and governmental agencies responsible for monitoring and forecasting HAB occurrences and effects. The information generated by this study provides the first detailed study of the lipid composition of this economically and environmentally important organism.
Technical Abstract: The harmful marine dinoflagellate, Karenia brevis, frequently forms large toxic blooms in the waters off the west coast of Florida (USA), and is responsible for massive fish kills and public health concerns. Despite decades of field studies on this organism, no investigation has yet examined the lipid composition of a K. brevis bloom event. To address this lack of information, samples from a 1999 K. brevis bloom from the northwest Florida coast were analyzed for their fatty acid and sterol composition. Fatty acids found in lipid fractions containing membrane phospholipids, chloroplast-associated glycolipids, and storage triglycerides, respectively, differed significantly. The glycolipid fraction was found to contain octadecapentaenoic acid [18:5(n-3)], a fatty acid commonly associated with dinoflagellates. The phospholipid fraction was found to contain small amounts of the recently discovered highly-unsaturated fatty acids, octacosaoctaenoic acid p28:8(n-3)] and octacosaheptaenoic acid [28:7(n-6)]. Triglyceride-associated fatty acids were more abundant than those associated with glycolipid or phospholipids. Sterols were found mainly as free sterols, and were dominated by two compounds, (24S)-4 alpha-methyl-5 alpha-ergosta-8(14),22-dien-3 beta-ol (ED) and its 27-nor derivative (NED). The implications of this data in the context of the physiological autecoloty of K. brevis are discussed.